Modern data processing systems, such as general purpose computer systems, allow the users of such systems to create a variety of different types of data files. For example, a typical user of a data processing system may create text files with a word processing program such as Microsoft Word or may create an image file with an image processing program such as Adobe's PhotoShop. Numerous other types of files are capable of being created or modified, edited, and otherwise used by one or more users for a typical data processing system. The large number of the different types of files that can be created or modified can present a challenge to a typical user who is seeking to find a particular file which has been created.
Modern data processing systems often include a file management system which allows a user to place files in various directories or subdirectories (e.g. folders) and allows a user to give the file a name. Further, these file management systems often allow a user to find a file by searching for the file's name, or the date of creation, or the date of modification, or the type of file. An example of such a file management system is the Finder program which operates on Macintosh computers from Apple Inc. of Cupertino, Calif. Another example of a file management system program is the Windows Explorer program which operates on the Windows operating system from Microsoft Corporation of Redmond, Wash. Both the Finder program and the Windows Explorer program include a find command which allows a user to search for files by various criteria including a file name or a date of creation or a date of modification or the type of file. However, this search capability searches through information which is the same for each file, regardless of the type of file. Thus, for example, the searchable data for a Microsoft Word file is the same as the searchable data for an Adobe PhotoShop file, and this data typically includes the file name, the type of file, the date of creation, the date of last modification, the size of the file and certain other parameters which may be maintained for the file by the file management system.
Certain presently existing application programs allow a user to maintain data about a particular file. This data about a particular file may be considered metadata because it is data about other data. This metadata for a particular file may include information about the author of a file, a summary of the document, and various other types of information. A program such as Microsoft Word may automatically create some of this data when a user creates a file and the user may add additional data or edit the data by selecting the “property sheet” from a menu selection in Microsoft Word. The property sheets in Microsoft Word allow a user to create metadata for a particular file or document. However, in existing systems, a user is not able to search for metadata across a variety of different applications using one search request from the user. Furthermore, existing systems can perform one search for data files, but this search does not also include searching through metadata for those files.
Prior existing systems perform indexing of the full content of user files either upon user request or upon a scheduled time.